Process for the integral recovery of the sulphur contained in spent lead batteries, obtained in the form of pure sulphuric acid for reuse in the production of new batteries

Abstract

A process is disclosed for recovering the components of spent lead acid batteries of the type comprising an active mass desulphurization stage in which sodium sulphate is formed, characterized in that the sodium sulphate solution thus formed is fed to an electrolysis stage in which a soda solution is produced at the cathode and a sulphuric acid solution is produced at the anode. The soda solution produced at the cathode is recycled to the active mass desulphurization stage, and the sulphuric acid solution produced at the anode is recovered for reuse as battery electrolyte in the production of new lead acid batteries.

We claim: 
     
       1. A process for recovering the components of spent lead acid batteries comprising: (A) subjecting said batteries to desulphurization in a desulphurization stage to form a sodium sulphate solution; then   (B) subjecting said sodium sulphate solution to electrolysis in a device having an anode and a cathode and producing a sulphuric acid solution at said anode and a soda solution at said cathode; and then   (C) recycling said soda solution to said desulphurization stage and recovering said sulphuric acid solution for reuse as a battery electrolyte in the production of new acid lead batteries.   
     
     
       2. The process as claimed in claim 1, further comprising the steps of initially removing sulphuric electrolyte from said spent lead batteries and neutralizing said sulphuric electroltye using a portion of said soda solution produced in said electrolysis step. 
     
     
       3. The process as claimed in claim 1, further comprising the steps of concentrating said sulphuric acid solution before recovering said sulphuric acid solution and concentrating said soda solution before recycling said soda solution. 
     
     
       4. The process as claimed in claim 3, wherein said electrolysis step comprises conducting electrolysis in a double ionic membrane electrolytic cell. 
     
     
       5. The process as claimed in claim 4, wherein said step of concentrating said sulphuric acid solution comprises concentrating said sulphuric acid solution to 35% by weight, and said step of concentrating said soda solution comprises concentrating said soda solution to 20% by weight. 
     
     
       6. The process as claimed in claim 1, further comprising the step of adjusting the pH value of said sodium sulphate solution to a predetermined value prior to recycling said sodium sulphate solution, said predetermined value representing a minimum lead solubility in a alkaline solution. 
     
     
       7. The process as claimed in claim 6, wherein said step of adjusting said pH comprises adjusting said pH to 9.2. 
     
     
       8. The process as claimed in claim 1, wherein said step of producing a soda solution at said cathode comprises producing sodium hydroxide. 
     
     
       9. The process as claimed in claim 1, wherein said step of subjecting said batteries to desulphurization comprises the step of desulphurisizing said batteries using sodium hydroxide.